After the Dacic wars (101-102, 105-106), Dacia was conquered and organized by Traian as a Roman province. The effective roman occupation of Dacic territories included Oltenia, Banat, and a side of Transylvania. In the north, the limit of province was established on the Some ∘ River. In east the border was established on the western rivers of Volcanic Mountains . Ptolemy (2nd century P.C.) considered that Roman Dacia included not only Oltenia and Banat but all Transylvania and Muntenia too, up to Siret River. Archeological discoveries contravene to this affirmation. In Moldavia, the vallum from Siret river embouchure to the Oituz canyon and the two settlements from Barbosi and Poiana are evidences that Romans were not present north of this line. Muntenia was not effectively occupied by Romans but was a cliental region (Ad Moesiam) . In north and east the province neighbored upon free Dacs (Costobocs and Carps), Sarmats, and Buri; in west Quadi and Marcomans. But the borders were not exactly defined; Dacia was not absolutely separated from other Dacic territories, still under the dominance of free Dacs. .
Traian undertook a great reorganization of Roman defensive system at Danube. The new province was included in this system. The reorganization was administrative and military. As an effect were built roads, the commerce was stimulated, and urban life flourished. The peace with barbarians was ensured by means of gifts and threats and especially by army and border fortifications. In this way the civil life and Romanism in Danubian provinces were enforced and the resistance to the barbarian attacks raised. In order to enforce the civil life of the new province, Dacia was colonized whit Roman from other provinces (Eutropius). .
Dacia gave the Empire many resources, especially gold, but likewise salt, wood, cattle, and grain. In order to exploit these resources, and especially for mining, in province were settled miner colonists from Dalmatia .
